Weeds Act - Frequently Asked Questions


Table of Contents

Why does Ontario have the Weed Control Act?

The intent of the Weed Control Act is:

  1. To reduce the infestation of noxious weeds that negatively impact on the industries of agriculture and horticulture.
  2. To reduce plant diseases by eliminating plant disease hosts such as common barberry and European buckthorn.
  3. To reduce health hazards to livestock caused by poisonous plants.

How do I contact my local area or municipal weed inspector?

Your local municipality, region, district or county should be able to provide you with contact information regarding the Weed Inspector or local by-law enforcement officer for your area.

What is a noxious weed?

In general terms the definition of noxious is:

  • Harmful to living things; injurious to health.

In Ontario, 23 weeds are considered noxious under the Weed Control Act. A list of these 23 noxious weeds can be found on the Weed Control Act home page.

Why is milkweed on the list of noxious weeds in Ontario?

Common milkweed can be a very difficult weed to control in many field crops thereby causing significant reductions in crop yield and quality. This can have a considerable negative impact to a grower's net economic return. In the last 10 years, new herbicide technologies have greatly improved the control of common milkweed in field crops. However control of common milkweed around field borders is essential as it minimizes seed spread into fields and therefore reduces the reliance on herbicides for "in field" control.

Common milkweed when consumed in large quantities is poisonous to livestock. Therefore minimizing populations in actively pastured land will greatly reduce the chance of any adverse health affects to livestock.

For more information on Milkweed and the Weed Control Act, refer to the article entitled: "Milkweed Species in Ontario".

Can I plant milkweed in my garden?

As long as the population of milkweed planted doesn't negatively affect agricultural or horticultual land by spreading seed and new vegetative plant material (i.e. root stock) into fields, nurseries or greenhouses then it is acceptable to plant milkweed in your garden. It is recommended that you consult with your local weed inspector and/or neighbours so that all parties involved are comfortable that the impact to agriculture or horticulture is negligible.

Learn more:


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: Mike Cowbrough, Weed Management Field Crops Program Lead/OMAF
Creation Date: 22 March 2005
Last Reviewed: 08 August 2008